Role of
Photogrammetry and Remote Sensing in Wenchuan Earthquake Deren Li
It has been demonstrated that photogrammetry and remote sensing has played a crucial role in the aftermath of the earthquake in Wenchuan, Sichuan
Phase II was marked by the prevention of
and preparedness for secondary disasters,
i.e., landslides and mudslides, especially,
those in and around the quake lakes or
barrier lakes. Figure 5 clearly highlights the change of river water ways due to the
forming of quake lakes in Tangjiashan,
as indicated by white regions generated
by comparing SPOT5 (10 m resolution)
images taken before (November 10,
2006) and after (May 16, 2008) the
earthquake. Figure 6 shows the DEM of
the quake lake in Tangjiashan, Mianyang
city, Sichuan Province, one of the area
worst affected by Wenchuan earthquake,
which was generated based on ALS50 II
air-borne LiDAR data with a sampling
interval of 2 m, flight date, May 31, 2008, by the State Bureau of Surveying
and Mapping and Wuhan University
(the barrier dam is shown with an inset
picture) in collaboration. The boundaries
of rivers in the quake lakes, Tangjiashan,
Mianyang city, Sichuan Province, are
shown in Figure 7, as indicated by the
green lines against the backgroundRadarsat imagery at a resolution of
7 m, acquired on May 17, 2008.
Figure 7. The boundaries of rivers in the quake lakes, Tangjiashan, Mianyang
city, Sichuan Province, as indicated by the green lines against the background
Radarsat imagery at a resolution of 7 m, acquired on May 17, 2008.
In addition to disaster relief efforts,
D-inSAR can also be used for scientific
research on
earthquake.
Preliminary
results derived
from ALOS
PALSAR
satellite
acquisition on
June 11, 2008
are released
at www.gmat.
unsw.edu.
au/LinlinGe/
Earthquake, as
shown in Figure
8, thanks to the
efforts of the
team led by Dr Linlin Ge. Dr Ge used predicted orbit
data in order to produce and deliver the
result in NEAR REAL-TIME: 17 hours
and 46 minutes, from image capture to
results posting on web. The Japanese
ALOS PALSAR sensor acquired the Path
477 image on 11 June 2008 1:37 Sydney
Time AEST (10/06/2008 15:37:07 UTC;
10/06/2008 23:37 Bejing Time). Image
data were available to download from
ERSDAC at 11:24AM. Image data (using
predicted orbit) were downloaded to
UNSW on 11/06/2008 at 16:55. D-InSAR
results were generated on 11/06/2008 at
19:05. Post-processed D-InSAR results
were uploaded on 11/06/2008 at 19:23.
Figure 8. The image showing the aftershocks, generated by
D-inSAR technology based on ALOS PALSAR sensor acquisition,
Path 477 image on 11 June 2008 1:37 Sydney Time AEST.
Some concluding remarks are as
follows. It has been demonstrated that
photogrammetry and remote sensing has
played a crucial role in the aftermath
of the earthquake in Wenchuan,
Sichuan. The rapid data acquisition and
information services, especially, those
featured with fully automatic, near realtime
remote sensing systems without
ground control, have contributed greatly
to the rescue work and disaster relief
efforts. The specialty of photogrammetry
and remote sensing is becoming
increasingly visible and its roles are
growingly recognized. It is important to
develop a national disaster rapid response
system that corroborates the work by
different agencies and facilitates data
and resources sharing. It is necessary to
further develop China’s National Spatial
Data Infrastructure. Moreover, it should
be on the agenda to enhance the capability
of high-resolution earth observation
systems. Last but not the least, it is
necessary to strengthen international
cooperation in spatial information
science and technology, like International
Charter and CEOSS from GEO.
Acknowledgements
Many institutions and people have helped
with data acquisition and provision of
materials during the project concerning
rapid response to Wenchuan earthquake.
The diligent work by and kind helps
from colleagues home and abroad
are gratefully acknowledged.
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